thermal: gov_user_space: Do not lock thermal zone mutex

thermal: gov_user_space: Do not lock thermal zone mutex

Commit 94b92f6db4ee ("thermal/core: Move the thermal zone lock out of
the governors") moved thermal zone locking away from governors, but it
forgot about the user space one which deadlocks now.

Fix this by removing the thermal zone locking from the user space
governor.

Fixes: 94b92f6db4ee ("thermal/core: Move the thermal zone lock out of the governors")
Tested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>